I made two changes:

1: I added to the ruby code to allow the user to add a gradient background to the chart.
2: I updated the SWF to a new public build from google code that allows gradient backgrounds: http://code.google.com/p/ofc-etw/ - gradient doesn't work with the version currently in the project

Note: The new SWF doesn't conflict with any previous OFC2 commands/code. Also, the generated JSON for the gradient follows the JSON found here: http://wiki.openflashchart.com/ofc2/features/background/inner/gradient